The present invention relates generally to automotive differentials and, more particularly, to a differential assembly including spring washers to place the differential gears in a zero lash condition.
Present differential assemblies are used in a drive train of motor vehicles for delivering drive torque to the wheels while permitting speed differentiation therebetween. In order to provide easily assembled and properly functioning differential gearsets, a lash or clearance is designed to exist between the pinion gears and the side gears within the differential assembly. Excessive lash has been known to cause a “clunk” sound that is sometimes audible to the driver when the vehicle changes direction of travel. While such noises emanating from the drive train may have been previously tolerated by original equipment manufacturers, the present acceptance level for such undesirable noises is low.
Additionally, some presently produced differential assemblies include a housing having a spherical cavity in receipt of partially spherically shaped pinion gears and side gears. The use of spherically shaped components has allowed for increased structural durability of the driveline components and may be desirable. Furthermore, spherical shapes are easier to manufacture and allow tighter tolerances that provide for reduced lash between the gears. The use of spherically shaped side gears has substantially reduced the “back face” area on which a spring or other biasing device may be positioned to bias the side gears toward the pinion gears to reduce gear lash. As such, use of a relatively large Belleville washer adjacent to a side gear having a relatively large planar back surface area is no longer a feasible design solution. Accordingly, it may be desirable to produce a differential assembly having spherically shaped components using spring washers to provide a zero lash assembly.
The present invention differential assembly includes a differential housing adapted to be rotatably driven by an input shaft. The housing includes a chamber having a substantially spherically shaped inner surface with shaft openings at opposite ends of the chamber. A pair of side gears are rotatably positioned in the chamber. The side gears are adapted to be non-rotatably mounted to output shafts which extend through the shaft openings. Each side gear includes a spherically shaped surface with a trunnion having an end face. A pair of differential pinions are rotatably mounted within the chamber. The pinions have a longitudinal axis perpendicular to the axis of the side gears with each of the pinions being meshed with each of the side gears. Each of the pinions includes a spherically shaped surface. A pair of pinion thrust washers each having spherically shaped inner and outer surfaces are positioned between the housing inner surface and one of the spherically shaped surfaces of the pinion. Similarly, a pair of side gear thrust washers each has spherically shaped inner and outer surfaces. Each of the side gear thrust washers are positioned between the housing inner surface and one of the spherically shaped surfaces of the side gears. A pair of springs are positioned within the chamber. Each spring is engaged with one of the end faces of the side gears to minimize gear lash between the side gears and the pinion gears.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.